SDA5523 Micronas Semiconductor, SDA5523 Datasheet - Page 22

• Manufacturer Part Number: SDA5523
• Description: SDA55xx TVText Pro
• Manufacturer: Micronas Semiconductor

SDA 55xx
2.2.8.1.8. Data Pointer Register (DPTR).
Table 2–8: Related registers
The 16-bit Data Pointer Register DPTR is the concate-
nation of registers DPH (high-order Byte) and DPL
(low-order Byte). The DPTR is used in register-indirect
addressing to move program memory constants and to
access the extended data memory. DPTR may be
manipulated as one 16-bit register or as two indepen-
dent 8-bit registers DPL and DPH.
Eight data pointer registers are available, the active
one is selected by a special function register (DPSEL)
2.2.8.2. CPU Timing
Timing generation is completely self-contained, except
for the frequency reference which can be a crystal or
external clock source. The on-board oscillator is a par-
allel anti-resonant circuit. The XTAL2 pin is the output
of a high-gain amplifier, while XTAL1 is its input. A
crystal connected between XTAL1 and XTAL2 pro-
vides the feedback and phase shift required for oscilla-
tion.
In slowdown mode, the microcontroller runs at one
fourth the normal frequency. This mode is useful when
power consumption needs to be reduced. Slow down
mode is entered by setting the bit SD in PCON regis-
ter.
Note: Any slow-down mode should only be used if
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Register Name
DPL
DPH
DPSEL
See Section 3. on page 110 for detailed register description.
teletext reception and the display are disabled.
Otherwise processing of the incoming text data
might be incomplete and the display structure
will be corrupted. For disabling acquisition and
display generator see Section 2.3.17.
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Sept. 10, 2004; 6251-556-3DS
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2.2.8.3. Addressing Modes
There are five general addressing modes operating on
Bytes. One of these five addressing modes, however,
operates on both Bytes and bits:
– Register
– Direct (both Bytes and bits)
– Register indirect
– Immediate
– Indirect, using base register plus index-register
The following list summarizes, which memory spaces
may be accessed by each of the addressing modes:
Register Addressing
R0 … R7
ACC, B, CY (bit), DPTR
Direct Addressing
RAM (low part)
Special Function Registers
Register-indirect Addressing
RAM (@R1, @R0, SP)
Immediate Addressing
Program Memory
Base Register plus Index-Register Indirect
Addressing
Program Memory (@DPTR + A, @PC + A)
Bit Name
DPH[7:0]
DPL[7:0]
3
2
DPSEL[2:0]
1
DATA SHEET
0
Micronas